Recommendation regarding the cranial upper border of level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma

Table 2 Distribution of upper lymph nodes in level IIb

Level IIb	Number (percentage) of patients
	LNc2		LNab
	Unilateral	Bilateral	Unilateral	Bilateral
Positive LNs	99 (29.9)	24 (7.25)	26 (7.85)	2 (0.60)
LN ≥ 5 mm	24 (7.25)	13 (3.93)	1 (0.3)	0 (0)

LNc2: level IIb LNs located above the C2 vertebra; LNab: LNs above the upper border of level IIb

ISSN: 1748-717X